1. Field of the Invention
The present invention relates to a communication network, and more particularly to a system and method for controlling a packet data service in a mobile communication network.
2. Background of the Related Art
In a related art IMT-2000/PCS/cellular mobile telephone system, a medium access control (hereafter MAC) layer is located between a terminal and a base station system to effectively transfer packet data therebetween. A packet data service active terminal and a base station system interact to maintain four states of such a MAC layer, as shown in FIG. 1, according to the presence of data to be transferred. But, there is no MAC state under a packet data service inactive condition. The four MAC states are as follows.
The first MAC state is an active state where a traffic channel is assigned between a terminal and a base station to transfer packet data therebetween. In the active state, a power control operation is performed through a power control channel, and the packet data is transferred through the traffic channel under control of a radio link protocol (RLP) established between the terminal and a base station system.
The second MAC state is a control hold state where the traffic channel is released because no data is transferred between the terminal and the base station. In the control hold state, however, the power control channel and a radio resource control channel are assigned and a state of the RLP is maintained. In the control hold state, upon the occurrence of data to be transferred, the packet transfer is immediately performed by assigning only the traffic channel.
The third MAC state is a suspended state where the power control channel and the radio resource control channel that were held at the control hold state are released. In the suspended state, however, the RLP state and a state of a point-to-point protocol (PPP) are maintained between the terminal and the base station system. In the suspended state, upon the occurrence of data to be transferred, the packet transfer between the terminal and the base station system is rapidly resumed because the RLP state is maintained.
The fourth MAC state is a dormant state where a radio connection between the terminal and the base station system is completely released and only the PPP state is maintained between the terminal and a packet data node. In the dormant state, the substantially same amount of time as that in initial packet connection is required to resume the packet connection between the terminal and to base station system.
The MAC layer is located between the terminal and the base station system, and more particularly, between a radio network controller (RNC) of the base station system and the terminal to transfer the packet data therebetween on the radio side. When the terminal is under a packet data service active condition, the MAC layer maintains any one of the above four states. Such a MAC state is continuously maintained until the terminal is changed from the packet data service active condition to a packet data service inactive condition (for example, power off). At this time, the same MAC state should be maintained between the radio network controller and terminal. However, control information is required and must be present between the terminal and radio network controller to maintain the MAC state therebetween.
However, techniques associated with the MAC layer between the terminal and base station system are valid only when the MAC state is continuously maintained between the terminal and a new radio network controller even when the terminal moves from an area of an old radio network controller, from which it is currently receiving a packet data service, to an area of the new radio network controller. For this reason, in the case of handoff, the old radio network controller has to transfer all MAC state information of the terminal to the new radio network controller.
As described above, the related art system has various disadvantages. In the related art system, a handoff operation can be performed between the old and new radio network controllers only in the active state and the control hold state among the above-mentioned MAC states. Thus, the handoff operation cannot be executed at either the suspended state or the dormant state. As a result, there is a need to transfer MAC state information between the old and new radio network controllers.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.